End mills are used for groove cutting or side cutting of a work, in this case chips generated by the cutting need to be smoothly discharged. For example, Patent Document 1 describes providing multiple breaker flutes of three or more on a rake surface to improve chip separation from the rake surface in order to cope with the problem that chip gets entangled with an end mill body to cause chip clogging when a work having high ductility such as aluminum system is machined.